Fusible safety device for pressure fuel tanks



A. WHITE ETAL FUSIBLE SAFETY DEVICE FOR PRESSURE FUEL TANKS April 26, 1949.

Filed Nov. 15, 1943 //V VE /V 7 17/?5.

r/z Zmrr Patented Apr. 26, 1949 FUSIBLE SAFETY DEVICE FOR PRESSURE FUEL TANKS Abraham White, Welleslcy Hills, and Thurston Hartwell and Lawrence Reynolds, Needham, Mass, assignors to Barnstead Still & Sterilizer 00., Inc., Forest Hills, Mass., a corporation of Massachusetts Application November 15, 1943, Serial No. 510,368

This invention relates to safety devices embodying a fusible element constructed and arranged normally to seal a pressure fuel tank from the atmosphere but operating to break the seal when the temperature adjacent to the element becomes sufficiently high to fuse the element. The invention is especially applicable to liquid heating or vaporizing receptacles such as boilers, evaporators, distilling units, etc. where pressure burner systems are employed and where it is necessary to avoid over-heating and damage caused by low water or liquid level in a receptacle. In such use a tank or cylinder is employed to contain the fuel in liquid form for the burner and air pressure maintained in the tank will serve to force the fuel to the burner unit. The arrangement is such that a safe or normal level of liquid in the receptacle maintains the fusible element of our device below fusing temperature but should the liquid drop below a proper level the element will no longer be protected and will fuse and open the tank up to the atmosphere, thus relieving the tank pressure and cutting off the flow of fuel to the burner unit. The production of an improved safety device of this nature comprises the primary object of the invention.

These and other features of the invention will be best understood and appreciated from the following description of a preferred embodiment thereof selected for purposes of illustration and shown in the accompanying drawing in which,

Fig. 1 is a view in elevation of an evaporator or distilling apparatus employing the invention,

Fig. 2 is an enlarged sectional view through the fusible element and associated parts.

In the drawing we have illustrated a distilling apparatus embodying a liquid fuel tank 18 carrying two burners l2 associated with an evaporating vessel or receptacle M. A hand pump I6 is provided for placing the fuel under air pressure in the tank and from which it is forced upwardly through the pipes IE to the burners. The fiow of fuel to the burners is regulated by valves Hi.

The vessel I4 is supported above the tank by means of posts 20 and includes a metallic basin 22 having a flanged bottom located above the burners and a depression in its upper face for containing water or other liquid to be evaporated. The basin is supplied with liquid through the pipe 24 and a waste pipe is provided at 26. It will be understood that over-heating damage to the apparatus would be caused if the liquid level in the basin became excessively low, and the purpose of our invention is the provision of means for automatically preventing this possibility.

2 Claims. (01. 158-424) An air pressure pipe 28 extends upwardly from the fuel tank to a passage 30 formed in the body of the basin 22 and carries a pressure gauge 32. The passage is reentrant in shape and closed at its upper and outer end by a fusible disk 34 removably held in place by a shouldered hollow bushing 36 and a threaded bushing 38 screwed into the casting of the basin. The upper branch of the passage 30 containing the disk is located in the lower portion of the casting in which the evaporating basin is formed and where the casting is normally kept below the fusing temperature of the disk by the liquid therein. The upper branch of the passage lies below the rim of the depression contained within the basin 22. Should the liquid become wholly evaporated or dangerously low, the metal of the basin will become heated to a temperature fusing the disk 34 thereby opening the passage 30 to the atmosphere, releasing the air pressure in the tank In and thus stopping the flow of fuel to the burners.

The evaporating vessel I4 is herein shown as enclosed with a casing 23 and as communicating with a condenser 25 which is placed directly above it, but these elements form no part of the present invention.

It will be noted that the whole safety system, including the pipe 28, the passage 30, the fusible disk 34 and its annular retaining elements 36 and 38, is structurally independent of the burners and so may be installed at any convenient location in the apparatus. Moreover, the employment of a reentrant passage in the solid metal of the heated evaporating members of the apparatus is a novel and characteristic feature of our invention that contributes largely to the compact and successful construction of our invention in the form herein illustrated.

While we have herein illustrated our invention in connection with an evaporator having fuel burners associated directly therewith, it will be understood that the invention is not to be considered as limited specifically to such construction since it is apparent that the automatic releasing of the pressure in a closed tank by means of the fusible element combination herein disclosed is adaptable to various combinations and uses all of which are contemplated as being within the scope of the invention.

Having thus disclosed our invention and described in detail an illustrative embodiment thereof, we claim and desire to secure by Letters Patent:

1. In distilling apparatus having a, pressure fuel tank, an evaporator having a solid metal base with a liquid-holding depression in its upper face, the base having a U-shaped reentrant passage disposed with its branches one above the other and with the upper branch opening outwardly through the periphery of the base below the level of liquid in said depression, a replaceable fusible disk closing the end of said upper branch, and pressure connections leading from the fuel tank to the end of the lower branch of the passage, the fusible disk being located in proximity to the liquid-holding depression of the base and fusing in the event of an abnormal reduction in the said liquid level, thereby releasing pressure in the fuel tank.

2. An evaporator having a pressure fuel tank and an enclosed safety device, the evaporator comprising a vessel having a solid metal base with a liquid holding concavity in its upper face and a reentrant U-shaped passage extending into proximity of said concavity and having spaced branches which open outwardly through the periphery of the base, one branch having pressure connections to the fuel tank and the other branch containing a fusible disk and having a hollow bushing therein which holds the disk in sealing position within the base, the fusible disk being located in proximity to the concavity of the base and fusing in the event of an abnormal reduction of the liquid level in the concavity, thereby releasing pressure in the fuel tank.

ABRAHAM WHITE. THURSTON HARTWELL. LAWRENCE REYNOLDS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

